If you’ve been diagnosed with CIRS (Chronic Inflammatory Response Syndrome), and you’ve been down the rabbit hole of tick-borne infections and chronic mystery symptoms, you know how frustrating it can be to chase clarity with test after test—only to come up empty. That’s what makes this study out of France so important. Published in Infectious Disease Reports in 2021, it quietly but powerfully reshapes how we think about diagnosing vector-borne infections (VBIs). Spoiler: it’s not about testing harder. It’s about testing smarter.
Here’s what the researchers did—and why their work matters for anyone navigating the complex terrain of infection-triggered illness.
🔎 The Study: What They Did
The researchers followed 104 patients with chronic, complicated symptoms that started after a suspected tick bite. In France, this is called SPPT (Syndrome Persistant Polymorphe Post-Tique). Here, it often falls under the broader umbrella of post-treatment Lyme or VBI-triggered CIRS.
Instead of sticking to the usual script—run one blood test and call it a day—they tested four different body fluids:
- Saliva
- Urine
- Capillary blood (from a finger prick)
- Venous blood (from a standard blood draw)
Then they did something brilliant: they ran these tests twice, on different days. Because as it turns out, timing and tissue type can make all the difference.
📈 The Results: Infections Detected (and How Often)
Here’s what they found:
This isn’t just a lab table—it’s a wake-up call. The pathogen that gets all the press (Borrelia, aka Lyme) wasn’t even the most common. Other bugs like Mycoplasma, Rickettsia, and Ehrlichia were more prevalent, and many patients had more than one infection.
Notably, only 11.5% of patients tested completely negative for all organisms. That means nearly 9 out of 10 had at least one detectable infection—many had multiple.
📊 Why Sample Type Matters (More Than You Think)
Here’s where it gets really interesting. The type of sample they tested made a huge difference:
- Saliva detected the most infections
- Then urine
- Then capillary blood
- And venous blood—the most common and conventional choice—was dead last
So if your test came back negative, but your symptoms are screaming otherwise, it might not be you. It might just be the test looking in the wrong place.
⏲ Why Testing on Multiple Days Matters
Another major finding: doing PCR testing on more than one day uncovered more infections. Some bugs showed up on Day 1, vanished on Day 2—and vice versa.
Bottom line:
- A positive PCR result is always meaningful
- A negative PCR might be meaningless, especially if it’s one-and-done or taken from low-yield samples
This helps explain why someone can have conflicting results across tests—or test positive one month and negative the next. It’s not inconsistency. It’s biology.
🧬 DNA vs. RNA PCR: What’s the Difference?
The French researchers used DNA PCR, which detects genetic fragments of a microbe. But does that mean the infection is active?
RNA PCR: In Theory, A Better Answer
RNA PCR is designed to detect active infection, since RNA breaks down quickly when an organism dies. It’s a nice idea—if it worked reliably.
In reality:
- RNA is extremely fragile, and hard to preserve during transport
- False negatives are common because it degrades before it gets to the lab
So while RNA PCR might offer cleaner answers, DNA PCR is more reliable in practice. And a positive DNA PCR still tells us: this organism is (or was) in your system. It’s a piece of the puzzle.
🔍 Context is Everything
PCR results, like all data, only matter when they’re interpreted in context. A positive result needs to be read alongside other clues:
- Are immune activation markers like IL-6, IL-8, VEGF, or CCL5 elevated?
- Do your symptoms line up with what we’d expect from that pathogen?
- Do you respond to treatment, whether that means improvement or a temporary Herxheimer flare?
No single test gives us the full picture. But several well-placed pieces can reveal what’s really going on under the surface.
🫰 Why This Matters for VBI-Triggered CIRS
If you’re dealing with chronic, relapsing symptoms after a tick bite—or even without a clear exposure—this study might feel like someone finally handed you a flashlight in the dark.
- It validates the realness of your experience
- It reminds us that Borrelia is only part of the story
- And it reinforces the idea that how and when we test matters just as much as what we’re testing for
The takeaway? You don’t need more guesswork. You need a testing strategy that looks at multiple systems, multiple sample types, and more than one point in time. Because infections don’t always announce themselves neatly. But when we start listening differently, we often find what’s been there all along.
Raffetin A, Perronne C, Bouiller K, et al. Persistent polymorphic syndrome possibly due to a vector-borne infection: A French prospective cohort study. Infect Dis Rep. 2021;13(4):964–976. doi:10.3390/idr13040088